Shut-off valve having two valve seats providing pressure equalization

ABSTRACT

A shut-off valve that has particular application for opening and closing a compressed hydrogen storage tank. In one embodiment, the valve includes two valve sealing members where one side of one valve sealing member is on the high pressure side of the valve and an opposing side of the other valve sealing member is on the high pressure side of the valve. Therefore, the pressure applied to the two valve sealing members offset each other so that less force is required to open the valve against the high pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. patent applicationSer. No. 11/640,162, titled Shut-Off Valve Having Two Valve SeatsProviding Pressure Equalization, filed Dec. 15, 2006, which is aDivisional application of U.S. patent application Ser. No. 11/155,184,titled Hydrogen valve with Pressure Equalization, filed Jun. 17, 2005,now U.S. Pat. No. 7,219,695.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a valve including pressureequalization and, more particularly, to a shut-off valve for acompressed hydrogen tank, where the valve includes two valve seats andtwo inlet ports that provide pressure equalization so that the valve canbe opened with reduced force at high inlet pressures.

2. Discussion of the Related Art

Hydrogen is a very attractive fuel because it is clean and can be usedto efficiently produce electricity in a fuel cell. The automotiveindustry expends significant resources in the development of hydrogenfuel cell systems as a source of power for vehicles. Such vehicles wouldbe more efficient and generate fewer emissions than today's vehiclesemploying internal combustion engines.

A hydrogen fuel cell is an electro-chemical device that includes ananode and a cathode with an electrolyte therebetween. The anode receiveshydrogen gas and the cathode receives oxygen or air. The hydrogen gas isdissociated in the anode to generate free hydrogen protons andelectrons. The hydrogen protons pass through the electrolyte to thecathode. The hydrogen protons react with the oxygen and the electrons inthe cathode to generate water. The electrons from the anode cannot passthrough the electrolyte, and thus are directed through a load to performwork before being sent to the cathode. The work acts to operate thevehicle.

Many fuel cells are typically combined in a fuel cell stack to generatethe desired power. For example, a typical fuel cell stack for a vehiclemay have two hundred or more stacked fuel cells. The fuel cell stackreceives a cathode input gas, typically a flow of air forced through thestack by a compressor. Not all of the oxygen in the air is consumed bythe stack and some of the air is output as a cathode exhaust gas thatmay include water as a stack by-product. The fuel cell stack alsoreceives an anode hydrogen input gas that flows into the anode side ofthe stack.

In some vehicle fuel cell systems, hydrogen is stored in one or morecompressed gas tanks under high pressure on the vehicle to provide thehydrogen necessary for the fuel cell system. The pressure in the tankcan be upwards of 700 bar. In one known design, the compressed gas tankmay include an inner plastic liner that provides a gas tight seal forthe hydrogen, and an outer carbon fiber composite layer that providesthe structural integrity of the tank. Because hydrogen is a very lightand diffusive gas, the inner liner must be carefully engineered in orderto act as a permeation barrier. The hydrogen is removed from the tankthrough a pipe. At least one pressure regulator is provided that reducesthe pressure of the hydrogen within the tank to a pressure suitable forthe fuel cell system.

Further, a shut-off valve is required either in the tank or just outsideof the tank that closes the tank when the fuel cell system is off. Astiff spring is typically used to maintain the valve in the closedposition and prevent hydrogen leaks. Because the pressure in thecompressed hydrogen tank may be very high, the pressure differencebetween the inlet side and the outlet side of the shut-off valve may bevery large. Therefore, the force required to open the valve against thepressure difference and the spring bias is significant. Electromagnetsare sometimes used in these types of shut-off valves to open the valve.However, electromagnets are generally not the most desirable valvechoice because of the amount of energy required to open the valve, andthe size and weight of the electromagnet.

SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, a shut-offvalve is disclosed that has particular application for opening andclosing a high pressure compressed gas storage tank. In one embodiment,the valve includes two valve sealing members where one side of one valvesealing member and an opposing side of the other valve sealing memberand is on the high pressure inlet side of the valve. Therefore, thepressure applied to the two valve sealing members offset each other sothat less force is required to open the valve.

Additional features of the present invention will become apparent fromthe following description and appended claims, taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a shut-off valve including two valvesealing members that provide pressure equalization, according to anembodiment of the present invention;

FIG. 2 is a cross-sectional view of a shut-off valve including two valvesealing members for providing pressure equalization that has particularapplication for the inside of a high pressure gas storage tank,according to another embodiment of the present invention;

FIG. 3 is a cross-sectional view of the shut-off valve shown in FIG. 2within the high pressure gas storage tank; and

FIG. 4 is a cross-sectional view of a shut-off valve including a valvesealing member and a bellows for providing pressure equalization thathas particular application for the inside of a high pressure gas storagetank, according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the invention directed toa shut-off valve that provides pressure equalization is merely exemplaryin nature, and is in no way intended to limit the invention or itsapplications or uses. For example, the shut-off valve of the inventionhas particular application for a compressed hydrogen storage tank in afuel cell system. However, as will be appreciated by those skilled inthe art, the shut-off valve of the invention may have otherapplications.

FIG. 1 is a cross-sectional view of a shut-off valve 10 that hasapplication for opening and closing a compressed hydrogen storage tankin a fuel cell system, according to an embodiment of the presentinvention. The shut-off valve 10 includes a valve body 12 mounted to aflange 20 of a cylindrical support member 14 by bolts 16. Anelectromagnetic coil 18 is wound around the member 14, as shown. Themember 14 includes an internal bore 22 in which is positioned acylindrical pole piece member 24 also having an internal bore 26. Aspring 28 is positioned within the bore 26 against an inside surface ofthe cylindrical member 14, as shown. A shaft 32 is mounted to the polepiece member 24 opposite to the spring 28, and extends into a valvechamber 34 within the body 12.

The body 12 includes a first valve seat 42 and a second valve seat 44. Afirst annular sealing member 46 is mounted to the shaft 32 proximate thevalve seat 42 and a second annular sealing member 48 is mounted to theshaft 32 proximate the valve seat 44. The body 12 also includes twoinlet ports 36 and 38 and one outlet port 40. The inlet ports 36 and 38are at tank pressure, which may be upwards of 700 bar for a compressedhydrogen tank associated with a fuel cell system. This pressure from theinlet ports 36 and 38 is introduced into the chamber 34 so that itforces the sealing member 46 against the valve seat 42 and the sealingmember 48 away from the valve seat 44. This configuration provides thepressure equalization of the valve 10. The bias of the spring 28 incombination with the pressure equalization from the inlet ports 36 and38 forces the sealing member 46 to seat against the valve seat 42 andthe sealing member 48 to seat against the valve seat 44 when the coil 18is not energized. This is the default closed position of the valve 10when hydrogen flow is not desired.

The electromagnetic coil 18 is energized to open the shut-off valve 10.The magnetic field generated by the coil 18 moves the pole piece member24 and the shaft 32 against the bias of the spring 28 so that thesealing member 46 moves away from the valve seat 42 and the sealingmember 48 moves away from the valve seat 44. Therefore, hydrogenentering the inlet ports 36 and 38 is allowed to flow through thechamber 34 and out of the outlet port 40. Because of the pressureequalization, the electromagnetic force provided by the coil 18 does notneed to overcome the pressure within the tank, and therefore the amountof energy required to open the valve 10 against the bias of the spring28 does not need to be significant.

The shut-off valve 10 has particular application for a compressedhydrogen tank where the valve 10 would be positioned outside of thetank. However, in other designs, it may be desirable to provide theshut-off valve within the tank. FIG. 2 is a cross-sectional view of ashut-off valve 60 similar to the valve 10 that provides pressureequalization, and is designed for the inside of a pressure tank,according to another embodiment of the present invention. FIG. 3 is across-sectional view of the valve 60 positioned within a pressure tank62, where the shut-off valve 60 is mounted within a bore 64 of anadapter 66. The adapter 66 connects the pressure tank 62 to the outsideenvironment. The adapter 66 may contain several components, such assensors, valves, filters, etc., depending on the particular design. Inthis embodiment, a valve body 68 of the valve 60 is positioned withinthe bore 64. The valve body 68 includes a valve chamber 70, a firstvalve seat 72 and a second valve seat 74. An outlet port 86 extendsthrough the adapter 64 to the outside environment to remove hydrogenfrom the tank 62.

The valve body 68 is mounted to a flange 76 of a cylindrical member 78.An internal bore 80 extends completely through the member 78. Acylindrical pole piece member 82 is positioned within an expandedportion 88 of the bore 80 proximate the valve body 68, as shown. Thepole member 82 includes orifices 84 that allow the bore 80 to be influid communication with the chamber 70. A shaft 90 is mounted to thepole member 82, where the shaft 90 includes an internal bore 92 also influid communication with the bore 80 through a central bore 94 of themember 82. A filter 96 is mounted over the bore 80 at an open end of themember 78 to prevent particles and the like from entering the bore 80.

A first annular sealing member 100 is mounted to the shaft 90 proximatethe valve seat 72 and a second annular sealing member 102 is mounted tothe shaft 90 proximate the valve seat 74. A spring 104 is positioned inthe chamber 70 between and in contact with the sealing member 100 andthe pole member 82, as shown. An electromagnetic coil 106 is wrappedaround the cylindrical member 78 and is used to open the valve 60.

The valve 60 is shown in its closed position where the coil 106 is notenergized so that the spring 104 forces the first sealing member 100against the first valve seat 72 and the second sealing member 102against the second valve seat 74. Hydrogen pressure within the tank 62enters the bore 80 through the filter 96, then through the bore 94, andthrough the orifices 84 to apply pressure in combination with the springbias 104 against the sealing member 100 to force it against the valveseat 72. The hydrogen pressure within the tank 62 also enters asub-chamber 110 in the valve chamber 70 through the bore 92 to force thesealing member 102 away from the valve seat 74. Therefore, the highpressure within the tank 62 is equalized by this configuration. When thevalve 60 is to be opened, the coil 106 is energized which magneticallydraws the pole member 82 towards the left against the bias of the spring104 to lift the sealing member 100 off the valve seat 72 and the sealingmember 102 off the valve seat 74 to allow the hydrogen to flow from thechamber 70 into the outlet port 74.

FIG. 4 is a cross-sectional view of a shut-off valve 120 similar to theshut-off valve 60, where like elements are identified by the samereference numeral, according to another embodiment of the invention. Inthis embodiment, the second sealing member 102 and the second valve seat74 are eliminated, and are replaced with a bellows 122. The bellows 122is mounted to the valve body 68 and an end of the valve shaft 90 tocreate a bellows chamber 124. When the valve 120 is closed, highpressure from the tank 62 pushes the sealing member 100 against thevalve seat 72, and provides pressure to the bellows chamber 124. Thepressure in the bellows chamber 124 pushes against an opposite side ofthe sealing member 100 away from the valve seat 72 to provide thepressure equalization, as discussed above. When the coil 106 isenergized, the pole member 82 and the shaft 90 move to the left causingthe bellows 122 to contract. Because the valve 120 only has one valveseat, high precision production processes are not required.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion and from the accompanyingdrawings and claims that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention as defined in the following claims.

1. A valve comprising: a valve body defining a valve chamber therein,said valve body including a first inlet port, a second inlet port and anoutlet port, said valve body further including a first valve seat and asecond valve seat; a coil mounting structure mounted to the valve bodyand including an internal bore; an electromagnetic coil wound on thecoil mounting structure; a shaft extending from the internal bore of thecoil mounting structure into the valve chamber, said shaft including afirst sealing member mounted to the shaft proximate to the first valveseat and a second sealing member mounted to the shaft proximate thesecond valve seat; and a spring applying a spring bias to the shaft tocause the first sealing member to seat against the first valve seat andthe second sealing member to seat against the second valve seat, whereininput pressure applied to the first and second inlet ports causes thefirst sealing member to seat against the first valve seat and the secondsealing member to be forced away from the second valve seat to providepressure equalization.
 2. The valve according to claim 1 wherein thevalve is a shut-off valve for a compressed hydrogen tank.
 3. The valveaccording to claim 2 wherein the valve is positioned within thecompressed hydrogen tank.
 4. The valve according to claim 3 wherein thevalve body is mounted to an adaptor within the compressed hydrogen tank.5. The valve according to claim 1 wherein the shaft includes a widenedportion positioned within the internal bore of the coil mountingstructure.
 6. The valve according to claim 5 wherein the spring ispositioned within a bore in the widened portion of the shaft.
 7. Thevalve according to claim 1 wherein the first and second inlet portsextend through the valve body.
 8. The valve according to claim 1 whereinthe first and second sealing members are cylindrical sealing members. 9.A valve comprising: a valve body defining a valve chamber therein, saidvalve body including at least one inlet port and an outlet port, saidvalve body further including a first valve seat and a second valve seat;a coil mounting structure mounted to the valve body and including aninternal bore; an electromagnetic coil wound on the coil mountingstructure; a shaft extending from the internal bore of the coil mountingstructure into the valve chamber, said shaft including a first sealingmember mounted to the shaft proximate the first valve seat and a secondsealing member mounted to the shaft proximate the second valve seat,said shaft including a widened portion positioned within the internalbore of the coil mounting structure; and a spring positioned within abore in the widened portion of the shaft, said spring applying a springbias to the shaft to cause the first sealing member to seat against thefirst valve seat and the second sealing member to seat against thesecond valve seat, wherein input pressure causes the first sealingmember to seat against the first valve seat and the second sealingmember to be forced away from the second valve seat to provide pressureequalization.
 10. The valve according to claim 9 wherein the valve is ashut-off valve for a compressed hydrogen tank.
 11. The valve accordingto claim 10 wherein the valve is positioned within the compressedhydrogen tank.
 12. The valve according to claim 11 wherein the valvebody is mounted to an adaptor within the compressed hydrogen tank. 13.The valve according to claim 9 wherein the first and second sealingmembers are cylindrical sealing members.
 14. The valve according toclaim 9 wherein the at least one inlet port is a first inlet port and asecond inlet port.
 15. The valve according to claim 14 wherein the firstand second inlet ports extend through the valve body.
 16. A shut-offvalve for a compressed hydrogen storage tank, said valve comprising: avalve body defining a valve chamber therein, said valve body including afirst inlet port, a second inlet port and an outlet port, said valvebody further including a first valve seat and a second valve seat; acoil mounting structure mounted to the valve body and including aninternal bore; an electromagnetic coil wound on the coil mountingstructure; a shaft extending from the internal bore of the coil mountingstructure into the valve chamber, said shaft including a first sealingmember mounted to the shaft proximate the first valve seat and a secondsealing member mounted to the shaft proximate the second valve seat,said shaft including a widened portion positioned within the internalbore of the coil mounting structure; and a spring positioned within abore in the widened portion of the shaft, said spring applying a springbias to the shaft to cause the first sealing member to seat against thefirst valve seat and the second sealing member to seat against thesecond valve seat, wherein input pressure causes the first sealingmember to seat against the first valve seat and the second sealingmember to be forced away from the second valve seat to provide pressureequalization.
 17. The valve according to claim 16 wherein the valve ispositioned within the compressed hydrogen tank.
 18. The valve accordingto claim 17 wherein the valve body is mounted to an adaptor within thecompressed hydrogen tank.
 19. The valve according to claim 16 whereinthe first and second sealing members are cylindrical sealing members.